Describes a person who essentially ruins other people's fun, either because they openly disapprove of what other people are doing, or because their unpleasant attitude annoys or depresses everyone who would otherwise be enjoying themselves, if it weren't for that person acting like a 'wet blanket'.

The term is probably American in origin, first being used as slang in the mid 1800's. It was meant to compare a person to a wet blanket used to extinguish fires by smothering them, similar to how such a person would "extinguish" fun and excitement in social situations. Another, more modern interpretation of the term likens a dislikable or overbearing person to the aggravating, uncomfortable feeling of being covered by a blanket when it's wet.

"William was at the party last night and kept bumming everyone out by lecturing them about the 'dangers of alcohol and drugs'. Ha!"
"Yeah, that guy is such a wet blanket."

A person who seems determined not to have a good time and refuses to play or interact with others. Someone who generally has a negative attitude. In some cases people can become wet blankets because they cannot win the games the others are playing or continously lose, and as a result give up, becoming a wet blanket. It is important to note the continous offenses as a wet blanket can result in becoming a soggy biscuit.

1. Zane: "No, you guys always abuse me, I'm tired of playing, I quit!"
Us: "Don't be a wet blanket... You know what? You've done it to much, now you're just a soggy biscuit."